1. Field of the Invention
The present invention relates to a noncorrosive photoresist stripper composition containing the combination of (1) selected solvents; (2) selected amines; and (3) a selected corrosion inhibitor.
2. Description of the Prior Art
The photoresist stripper art is replete with numerous references to stripper compositions containing both a polar solvent and an amine compound. The presence of an amine in photoresist stripper compositions has been judged to be essential to effectively remove cross-linked resist films. However, amine-type photoresist strippers sometimes have a serious problem of corrosion, especially with aluminum substrates.
It is believed that the corrosion is caused in part by the ionization of water with the amine in post-stripping water rinse, as residual stripper solution may be retained on the substrate surface and/or substrate carrier after the stripping step. In other words, the amine component of the stripper composition does not corrode the substrate by itself, but can trigger water to cause the corrosion.
To solve this problem, an intermediate rinse step with an organic solvent has been used between the stripping step and the post-stripping rinse with water. For example, isopropyl alcohol is known to be useful for this purpose. However, such intermediate rinses are not necessarily desirable because overall stripping operation becomes more complicated and, furthermore, an additional solvent waste is produced. Accordingly, if amine-type strippers are to be further employed, there is a need to solve this corrosion problem without intermediate organic solvent wastes. The present invention provides such a solution.
Illustrative of references suggesting photoresist stripper compositions containing the combination of a polar solvent and an amine compound are the following:
1. U.S. Pat. No. 4,617,251, which issued to Sizensky et al. (Olin Hunt) on Oct. 14, 1986, teaches a positive photoresist stripping composition containing (A) selected amine compound (e.g., 2-(2-aminoethoxy)-ethanol; 2-(2-aminoethylamino)-ethanol; and mixtures thereof) and (B) selected polar solvents (e.g., N-methyl-2-pyrrolidinone, tetrahydrofurfuryl alcohol, isophorone, dimethyl sulfoxide, dimethyl adipate, dimethyl glutarate, sulfolane, gamma-butyrolactone, N,N-dimethylacetamide and mixtures thereof). The reference further teaches that water as well as dyes or colorants, wetting agents, surfactants and antifoamers may be added into this composition.
2. U.S. Pat. No. 4,770,713, which issued to Ward (J. T. Baker) on Sep. 13, 1988, teaches a positive photoresist stripping composition containing (A) a selected amide (e.g., N,N-dimethyl acetamide; N-methyl acetamide; N,N-diethyl acetamide; N,N-dipropyl acetamide; N,N-dimethyl propionamide; N,N-diethyl butyramide and N-methyl-N-ethyl propionamide) and (B) selected amine compound (e.g., monoethanolamine, monopropanolamine, methyl-aminoethanol). The patent also teaches this stripper may optionally contain a water miscible nonionic detergent (e.g., alkylene oxide condensates, amides and semi-polar nonionics).
3. U.S. Pat. No. 4,786,578, which issued to Neisius et al. (Merck) on Nov. 22, 1988, teaches a rinse solution used after a photoresist stripper, said rinse solution containing (A) a nonionic surfactant (e.g., ethoxylated alkylphenol, fatty and ethoxylate, fatty alcohol ethoxylate or ethylene oxide/propylene oxide condensate) and (B) an organic base (e.g., mono-, di-, or tri-ethanolamine).
4. U.S. Pat. No. 4,824,762, which issued to Kobayashi et al. on Apr. 25, 1989, teaches photoresist stripping post-rinse solution containing (A) glycol ether (e.g., diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether) and (B) an aliphatic amine (e.g., monoethanolamine or triisopropylamine).
5. U.S. Pat. No. 4,824,763, which issued to Lee (EKC) on Apr. 25, 1989, teaches positive-working photoresist stripping composition containing (A) triamine (e.g., diethylene-triamine) and (B) a polar solvent (e.g., N-methyl-2-pyrrolidone, dimethylformamide, butyrolactone, aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons).
6. U.S. Pat. No. 4,904,571, which issued to Miyashita et al. on Feb. 27, 1990, teaches printed circuit board photoresist stripper composition containing (A) a solvent (e.g., water, alcohols, ethers, ketones, chlorinated hydrocarbons and aromatic hydrocarbons); (B) an alkaline compound dissolved in said solvent (e.g., primary amines, secondary amines, tertiary amines, cyclic amines, polyamines, quaternary ammonium amines, sulfonium hydroxides, alkali hydroxides, alkali carbonates, alkali phosphates and alkali pyrophosphates); and (C) a borohydride compound dissolved in said solvent (e.g., sodium borohydride, lithium borohydride, dimethyl amine borone, trimethyl amine borone, pyridane borone, tert-butyl amine borone, triethyl amine borone, and morpholine borone).
7. U.S. Pat. No. 5,279,791, which issued to Lee (EKC) on Jan. 18, 1994, teaches a stripping composition for removing resists from substrates containing (A) hydroxylamine (e.g., NH.sub.2 OH); (B) at least one alkanolamine; and optionally (C) at least one polar solvent.
8. U.S. Pat. No. 5,334,332, which issued to Lee (EKC) on Aug. 2, 1994, teaches the use of ethylenediamine tetraacetic acid and 1,2-dihydrobenzene as a chelating reagent to reduce the surface metal contamination on wafers.
9. German Published Patent Application No. DE3828513, which issued to Schulz (Merck) on Mar. 1, 1990, teaches a positive and negative photoresist stripper composition containing (A) an aprotic polar solvent (e.g., 1,3-dimethyl-2-imidazolidinone or 1,3-dimethyl-tetrahydro-pyrimidinone); and (B) an organic base (e.g., alkanolamine).
10. Japanese Published Patent Application No. 56-115368, which was published on Sep. 10, 1981 and is assigned to San Ei Chemical Industries, KK, teaches a photoresist stripping composition containing (A) nonionic surface activator (e.g., a polyethylene glycol ether); (B) organic solvent (e.g., cyclohexanone); and (C) either a swelling agent (e.g., polyethylene glycol) or penetrant (e.g., 2-aminoethanol).
11. Japanese Published Patent Application No. 63-208043, which issued to R. Ohtani (Kanto Chemical) on Aug. 29, 1988, teaches a positive-working photoresist stripper composition containing (A) 1,3-dimethyl-2-imidazolidinone; (B) a water-soluble organic amine (e.g., monoethanolamine, 2-(2-aminoethoxy)-ethanol, triethylene(tetramine). The application also teaches a surfactant may be added to the stripper.
12. Japanese Published Patent Application No. 64-088548, which issued to S. Shiotsu (Nagase Denshi Kagaku) on Apr. 3, 1989, teaches the use of 2-butyne-1,4-diol as a corrosion inhibitor for a positive photoresist stripper.
13. Japanese Published Patent Application No. 1-081949, which issued to K. Matsumoto (Asahi Chemical) on Mar. 28, 1989, teaches a positive-working photoresist stripper composition containing (A) gamma-butyrolactone, N-methyl-formamide, N,N-dimethylformamide, N,N-dimethyl-acetoamide or Nmethylpyrrolidone; (B) an amino alcohol (e.g., N-butyl-ethanolamine and N-ethyldiethanolamine); and (C) water.
14. Japanese Published Patent Application No. 4-124668, which issued to K. Wakiya (Tokyo Ohka) on Apr. 24, 1992, teaches the use of a phosphoric acid group containing surfactant as a corrosion inhibitor in a photoresist stripper.
15. Japanese Published Patent Application No. 4-350660, which issued to H. Goto (Texas Instruments, Japan and Kanto Chemical, Inc.) on Dec. 4, 1992, teaches a stripper for positive photoresists comprising (A) 1,3-dimethyl-2-imidazolidinone (DMI), (B) dimethylsulfoxide (DMSO) and (C) a water-soluble amine (e.g., monoethanolamine or 2-(2-amino-ethoxy)ethanol wherein the amount of the water-soluble amine is 7-30% by weight.
16. Japanese Published Patent Application No. 5-045894, which issued to Ward (ACT, Inc.) on Feb. 26, 1993, teaches the use of 6-hydroxyquinoline as a corrosion inhibitor in a positive photoresist stripper.
None of these references suggest the addition of such a chelating type corrosion inhibitor that has a divalent or polyvalent carboxylic acid group and is readily soluble in organic solvents such as N-methylpyrrolidone, N,N'-dimethyl-2 imidazolidinone, or related cyclic amides. Ethylenediamine tetraacetic acid (EDTA), which is one of typical polyvalent carboxylic acid-containing chelating reagents, was disclosed as a stripper ingredient in U.S. Pat. No. 5,334,332, which issued to Wai M. Lee on Aug. 2, 1994, however, EDTA or its analogues have least solubility in such organic solvents that are usually used in the stripper formulation so that they cannot well perform especially in order to prevent the corrosion.